His challenge was unanimously “dismissed with prejudice.”

There will be an appeal to the Minnesota Supreme Court (if there are any justices left to hear the case) and then probably to the federal courts, but the current time estimate is that Franken will be seated sometime in May or June.  A couple of wildcard considerations are whether Republican Governor Tim Pawlenty will sign the certification, and whether the Republicans will filibuster, the threat of which has caused the Democrats to back down in pretty much every confrontration this year.